[PATCH v3 00/18] nvmem: core: introduce NVMEM layouts

[Michael Walle <michael@walle.cc>]

This is now the third attempt to fetch the MAC addresses from the VPD
for the Kontron sl28 boards. Previous discussions can be found here:
https://lore.kernel.org/lkml/20211228142549.1275412-1-michael@walle.cc/


NVMEM cells are typically added by board code or by the devicetree. But
as the cells get more complex, there is (valid) push back from the
devicetree maintainers to not put that handling in the devicetree.

Therefore, introduce NVMEM layouts. They operate on the NVMEM device and
can add cells during runtime. That way it is possible to add more complex
cells than it is possible right now with the offset/length/bits
description in the device tree. For example, you can have post processing
for individual cells (think of endian swapping, or ethernet offset
handling).

The imx-ocotp driver is the only user of the global post processing hook,
convert it to nvmem layouts and drop the global post pocessing hook.

For now, the layouts are selected by the device tree. But the idea is
that also board files or other drivers could set a layout. Although no
code for that exists yet.

Thanks to Miquel, the device tree bindings are already approved and merged.

NVMEM layouts as modules?
While possible in principle, it doesn't make any sense because the NVMEM
core can't be compiled as a module. The layouts needs to be available at
probe time. (That is also the reason why they get registered with
subsys_initcall().) So if the NVMEM core would be a module, the layouts
could be modules, too.

Michael Walle (16):
  net: add helper eth_addr_add()
  of: base: add of_parse_phandle_with_optional_args()
  nvmem: core: fix device node refcounting
  nvmem: core: add an index parameter to the cell
  nvmem: core: move struct nvmem_cell_info to nvmem-provider.h
  nvmem: core: drop the removal of the cells in nvmem_add_cells()
  nvmem: core: add nvmem_add_one_cell()
  nvmem: core: use nvmem_add_one_cell() in nvmem_add_cells_from_of()
  nvmem: core: introduce NVMEM layouts
  nvmem: core: add per-cell post processing
  nvmem: core: allow to modify a cell before adding it
  nvmem: imx-ocotp: replace global post processing with layouts
  nvmem: cell: drop global cell_post_process
  nvmem: core: provide own priv pointer in post process callback
  nvmem: layouts: add sl28vpd layout
  MAINTAINERS: add myself as sl28vpd nvmem layout driver

Miquel Raynal (2):
  nvmem: layouts: Add ONIE tlv layout driver
  MAINTAINERS: Add myself as ONIE tlv NVMEM layout maintainer

 Documentation/driver-api/nvmem.rst |  15 ++
 MAINTAINERS                        |  12 ++
 drivers/nvmem/Kconfig              |   4 +
 drivers/nvmem/Makefile             |   1 +
 drivers/nvmem/core.c               | 281 ++++++++++++++++++++++-------
 drivers/nvmem/imx-ocotp.c          |  34 ++--
 drivers/nvmem/layouts/Kconfig      |  23 +++
 drivers/nvmem/layouts/Makefile     |   7 +
 drivers/nvmem/layouts/onie-tlv.c   | 249 +++++++++++++++++++++++++
 drivers/nvmem/layouts/sl28vpd.c    | 153 ++++++++++++++++
 include/linux/etherdevice.h        |  14 ++
 include/linux/nvmem-consumer.h     |  17 +-
 include/linux/nvmem-provider.h     |  95 +++++++++-
 include/linux/of.h                 |  25 +++
 14 files changed, 834 insertions(+), 96 deletions(-)
 create mode 100644 drivers/nvmem/layouts/Kconfig
 create mode 100644 drivers/nvmem/layouts/Makefile
 create mode 100644 drivers/nvmem/layouts/onie-tlv.c
 create mode 100644 drivers/nvmem/layouts/sl28vpd.c

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2.30.2